Tungsten Filled 3-Dimensional Printed Lung Blocks for Total Body Irradiation.

Area of Science:

• Medical Physics
• Radiation Oncology
• Materials Science

Background:

• Lung blocks are crucial for reducing lung dose during total-body irradiation (TBI) to prevent radiation pneumonitis.
• Traditional Cerrobend blocks contain toxic materials like lead and cadmium, posing handling risks.
• Current manufacturing involves pouring molten Cerrobend, which can be labor-intensive and less accurate.

Purpose of the Study:

• To develop and evaluate a novel workflow for creating 3D-printed lung block shells filled with tungsten ball bearings.
• To offer a lead-free and more accurate alternative to conventional Cerrobend blocks for TBI.
• To streamline the lung block manufacturing process and reduce the use of toxic materials in clinical settings.

Main Methods:

• 3D-printed lung block shells were designed using in-house software and filled with tungsten ball bearings.
• Physical and dosimetric comparisons were conducted between 3D-printed blocks, physician-drawn blocks, and clinical Cerrobend blocks.
• Dose transmission was measured using ion-chamber and Electronic-Portal-Imaging-Device (EPID), with analysis of full-width-half-maximum (FWHM) and coefficient-of-variation (COV).

Main Results:

• 3D-printed blocks showed significantly lower geometric differences compared to Cerrobend blocks (p = .0002).
• Dosimetric measurements indicated dose transmission between 42%-48% for both 3D-printed and Cerrobend blocks.
• The coefficient-of-variation was significantly higher in 3D-printed blocks (4.2% ± 0.6%) versus Cerrobend blocks (2.6% ± 0.7%) (p < .0001).

Conclusions:

• A tungsten-filled, 3D-printed workflow for TBI lung blocks is feasible and serves as a viable alternative to Cerrobend.
• This method facilitates the removal of toxic materials from the clinical workflow.
• The 3D-printed blocks offer improved accuracy and reduced manufacturing effort for clinically useful lung blocks.